Non-invasive system and method for measuring blood pressure variability

Abstract

A non-invasive system and method for measuring blood pressure variability includes a cuff (20) pneumatically connected to a pump (14) to inflate the cuff to be wrapped around a limb (21) of a subject. A pressure sensor (18) is associated with the cuff for measuring cuff pressure (52). A photoplethysmogram sensor (26) attached to a fingertip in the same limb (21) of the subject and placed distal to the cuff for monitoring blood flow and recording a pulse plethysmograph signal. A control unit (12) connected to the pressure sensor (18) and the photoplethysmogram sensor (26) for simultaneously recording the cuff pressure and the plethysmograph signal such that an empirical relationship is derived between the cuff pressure and an amplitude measure of the plethysmograph signal (54) to measure short-term variation in systolic and diastolic blood pressures at a frequency corresponding to respiratory cycle.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to a blood pressure measuring system, and more particularly relates to a non-invasive blood pressure measuring system for measuring a range of systolic and diastolic pressure and their short-term variability.BACKGROUND OF THE INVENTION[0002]Hypertension is a disease of world-wide significance. The criteria for diagnosis of hypertension are: systolic pressure >140 mmHg and / or diastolic pressure >90 mmHg. For Isolated Systolic Hypertension (ISH) which is the commoner type occurring in older individuals beyond 60 years of age, the criterion is: systolic pressure >140 mmHg and diastolic pressure <90 mmHg.[0003]Blood pressure is a highly varying signal, with the systolic and diastolic pressures varying from beat to beat, at a frequency which is often a respiratory frequency. This phenomenon is termed as blood pressure variability (BPV). Given BPV, single point criteria as mentioned in the previous paragraph a...

AI Technical Summary

Benefits of technology

[0015]It is, therefore, one aspect of the present invention to provide an improved cost-effective non-invasive blood pressure measuring system and method that is capable of estimating a range of systolic and diastolic pressures and their short-term variability during the recording.

[0016]It is another aspect of the present invention to provide an improved blood pressure measuring system that utilizes a pne...

Problems solved by technology

Given BPV, single point criteria as mentioned in the previous paragraph are inadequate to detect hypertension.

Even ruling out white coat hypertension in which a patient's blood pressure is elevated during the examination process due to nervousness and anxiety caused by being in a clinical setting, blood pressure variability per se can lead to spurious diagnosis of hypertension.

However, it is not feasible in a clinic or in a ward to place an arterial catheter for pressure measurement.

One problem associated with the Korotkoff method is the assumption that there is no change in either systolic or diastolic pressures in the cardiac cycles during the cuff deflation phase.

Another problem is that the assessment of when the sounds begin and cease is subjective and the inter observer variation is high.

Furthermore, there is no assessment in the variations of systolic, diastolic and therefore mean pressures that occur with respiration and the pulse pressure assessment can be very erroneous depending on the profile of deflation.

Furthermore, all drawbacks of Korotkoff method also apply to the oscillometric method.

However, the inflate...

Images